1. Field of the Invention
The present invention relates to a sheet post-processing apparatus including a sheet aligning device that aligns sheets conveyed thereto in the case of staple processing and the like.
2. Description of the Related Art
When sheets subjected to image formation in an image forming apparatus is received and post-process processing such as staple processing and punching processing is performed in a sheet post-processing apparatus that applies post-processing, it is necessary to align the sheets prior to this post-process processing.
Conventionally, a first aligning plate and a second aligning plate that nip a bundle of sheets are provided, the first aligning plate and the second aligning plate are moved in a direction of the bundle of sheets, one of the aligning plates is provisionally fixed, and the other aligning plate is further moved in the direction of the bundle of sheets to perform alignment in a horizontal direction. A rotor having a paddle is rotated to bring the paddle into contact with the sheets conveyed thereto and the sheets are drawn in by the paddle and struck against a stopper to perform alignment in a vertical direction. (For example, JP-A-2006-124156).
However, when the number of sheets increases, the sheets less easily move to a side and alignment cannot be performed satisfactorily. If a force for moving the aligning plates is increased, when there are few sheets, the sheets bend and alignment of the sheets is disordered. In this way, in the conventional sheet aligning device, since only one kind of setting for an aligning operation can be performed, there is a problem in that it is difficult to set the aligning operation to appropriately perform alignment of sheets even when there are few sheets or many sheets.